The present invention relates to a receiving sheet for heat transfer recording used to making a record by transferring sublimable dye or the like on a heat transfer sheet in a heat transfer recording system such as a thermal printer.
Conventionally known receiving sheets for heat transfer recording include a synthetic paper having a receiving layer composed of saturated polyester resin or the like provided on one side thereof. This kind of the receiving sheet for heat transfer recording is used together with a heat transfer sheet comprising a film composed of polyethylene terephthalate having a heat transfer layer composed of sublimable dye, binder and the like provided on one side thereof. These sheets are overlapped together in such a manner that the heat transfer layer is brought into contact with the receiving layer, and the heat transfer sheet is heated from the back side thereof by a dot type heat sensitive means such as a thermal head or the like which generates heat while controlled by electric signals in accordance with image information to transfer the sublimable dye in the heat transfer layer onto the receiving layer, whereby a transferred image like a natural color photograph can be obtained.
When, however, the above conventional receiving sheet for heat transfer recording comprises a synthetic paper composed of a resin having low heat resistance such as a polyolefin resin or the like as a substrate, strain is caused in the synthetic paper by the heat applied thereto when the heat transfer is carried out, and thus the receiving sheet is curled after an image has been formed. Further, when synthetic paper composed of a resin having high heat resistance is used as the substrate, an image having sufficient optical density cannot be obtained, because the substrate has poor cushioning and heat insulating properties and the like.
To solve these problems, various trials have been carried out.
For example, Japanese Patent Application Kokai (Laid-Open) No. 62-198497 proposes a receiving sheet for heat transfer recording comprising as a substrate a sheet composed of a core member having a synthetic paper adhered to at least one side thereof. Although this proposal improves the anticurl property of the receiving sheet for heat transfer recording after an image has been formed thereon, a problem such as deficiency of the transferred image and the like arises, because this sheet is inferior to a sheet composed only of a synthetic paper in smoothness. Japanese Patent Application Kokai No. 60-236794 discloses a receiving sheet for heat transfer recording composed of a substrate on which a thermoplastic resin layer is formed. In this receiving sheet, however, a problem arises in that the receiving sheet cannot provide sufficient image reproducibility and is inadequately fed while printing depending on types of resins, and at the worst case the receiving sheet cannot be fed at all by being fused and adhered to a heat transfer sheet, and the like. Further, U.S. Pat. No. 4,774,224 proposes to use a resin-coated paper having small average roughness as a receiving sheet for heat transfer recording. Although this proposal improves the anticurl property of the receiving sheet for heat transfer recording after an image has been formed thereon, a problem arises in that the receiving sheet is inadequately fed while printing, an image having sufficient optical density cannot be obtained, and the like similar to the receiving sheet disclosed in Japanese Patent Application Kokai No. 60-236794.